L6229 Ver la hoja de datos (PDF) - STMicroelectronics

Número de pieza

componentes Descripción

Fabricante

L6229

DMOS DRIVER FOR THREE-PHASE BRUSHLESS DC MOTOR

STMicroelectronics 

Figure 7. Logic Input Internal Structure

5V

L6229

ESD

PROTECTION

D01IN1329

Figure 8. Pin EN Open Collector Driving

OPEN

COLLECTOR

OUTPUT

5V

REN

CEN

DIAG

5V

EN

ESD

PROTECTION

D02IN1378

Figure 9. Pin EN Push-Pull Driving

PUSH-PULL

OUTPUT

REN

CEN

DIAG

5V

EN

ESD

PROTECTION

D02IN1379

3.3 PWM CURRENT CONTROL

The L6229 includes a constant off time PWM Current Controller. The current control circuit senses the bridge

current by sensing the voltage drop across an external sense resistor connected between the source of the

three lower power MOS transistors and ground, as shown in Figure 10. As the current in the motor increases

the voltage across the sense resistor increases proportionally. When the voltage drop across the sense resistor

becomes greater than the voltage at the reference input pin VREF the sense comparator triggers the

monostable switching the bridge off. The power MOS remain off for the time set by the monostable and the mo-

tor current recirculates around the upper half of the bridge in Slow Decay Mode as described in the next section.

When the monostable times out, the bridge will again turn on. Since the internal dead time, used to prevent

cross conduction in the bridge, delays the turn on of the power MOS, the effective Off Time tOFF is the sum of

the monostable time plus the dead time.

Figure 11 shows the typical operating waveforms of the output current, the voltage drop across the sensing re-

sistor, the pin RC voltage and the status of the bridge. More details regarding the Synchronous Rectification and

the output stage configuration are included in the next section.

Immediately after the Power MOS turn on, a high peak current flows through the sense resistor due to the re-

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